Add GitlabCI, tweak composer.json

The builds are now able to complete. @jwilson3 please validate that these changes don't break your ddev setup.

mandclu → credited jwilson3 → .

Looks good from my end. Thanks for removing the minimum-stability in composer.json, which allows ddev composer outdated -D to run as expected as well as the CI builds to run as well.

Automatically closed - issue fixed for 2 weeks with no activity.